1. Field of the Invention
This invention relates to an outboard motor having an engine having intake conduits, more specifically, the present invention relates to an outboard with an engine in which a length of each intake conduit is variable.
2. Description of the Related Art
Outboard motors are typically mounted on a hull of a watercraft and include an engine disposed within a cowling of the motor such that a crankshaft of the engine extends generally vertically when the watercraft is under a running condition. For some engines, an effective length of each engine air intake conduit can be varied in accordance with an engine speed so as to, for example, obtain the inertia charge effect of air intake.
For example, in prior art document No. JP-A-2002-195118, respective right and left intake conduits are bifurcated so as to selectively have different effective lengths. Each such intake conduit has a valve to switch between effective conduit lengths. The respective valves are operated in accordance with information about operational conditions. The V-type engine, however, has a right bank and a left bank, and ignition times of cylinders of one bank are different from those of the other bank. Thus, the control of the effective lengths of the respective intake conduits for the cylinders of the right and left banks may be varied simultaneously and may not provide the optimum engine control suitable for the respective right and left cylinders.